The present invention relates to a printing machine with a colorant support and a transfer device to transfer colorant from a reservoir onto the colorant support, wherein the transfer device and the colorant support are arranged with respect to each other in such a manner that a first transfer zone is formed in which, during operation of the printing machine, a colorant is transferred from the transfer device onto the colorant support, and being provided with a delivery apparatus to deliver at least part of the colorant from the colorant support onto a printing medium or a transfer means.
Furthermore, the invention relates to a printing process with the following steps: transferring a colorant from a transfer device onto a colorant support, whereby at least portions of a continuous film of colorant are transferred onto the colorant support; delivering at least a portion of the colorant from the colorant support onto a printing medium or a transfer means.
WO-A1-01/72518, incorporated herein by reference as background art, discloses a printing process for the transfer of a colorant from a colorant support onto a printing medium or a transfer means, in which the colorant undergoes a volume and/or positional change brought about using a controlled energy-delivering device, thus transferring a printing dot onto the printing medium or the transfer means. Here, the colorant is placed on the colorant support in a manner than it forms an essentially continuous film. Localized energy is then applied to this film so that the film undergoes a localized change in volume or position, and the colorant in this region is transferred from the colorant support onto a printing medium or a transfer means.
Once the transfer action from the colorant support onto the printing medium has been completed, the homogeneity of the film of colorant on the colorant support has been compromised. There now exist regions in which the colorant has been at least partially removed form the colorant support, while in other regions the colorant still forms a film with its original thickness or original volume. If, for example, the colorant support is then replenished using the dipping roller principle using the same amount of colorant as before, then in the regions in which the colorant has been ablated, less colorant or colorant substance accumulates, while in regions in which no colorant has been ablated, a thicker layer of colorant is built up. In this manner, already by the second inking-up of the colorant support, the film of colorant which is produced is no longer homogeneous, but exhibits localized differences in volume and/or thickness.
Moreover, many of the print colorants in use contain relatively volatile solvents, and so regions of the colorant film which remain for a longer period on the colorant support without being ablated dry up. Thus, particularly in regions which are only infrequently ablated, the film of colorant may dry up and stick to the colorant support.